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Aluminum Filler Selection Chart

How to choose between ER4043 and ER5356, the two most common aluminum fillers, for common base alloys, with the service conditions that rule one of them out.

Ref WG-0213AWS A5.10

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

AWS A5.10 classifies bare aluminum and aluminum-alloy welding wires and rods. Two fillers cover most shop work. ER4043 is aluminum-silicon: fluid, crack-resistant and forgiving. ER5356 is aluminum-magnesium: stronger, stiffer to feed and a better color match after anodizing. The choice depends on the base alloy, strength needed, service temperature and finish.

How to use it

Identify the base alloy (for example 6061, 5052, 3003). Check the mill marking or the drawing.
Find its row. Note which filler is preferred and which is acceptable.
Check the service conditions in the key points. They can override the row.

Selection chart

Base alloy	Common filler	Notes
1100	ER1100 or ER4043	Pure aluminum; 4043 is easier to weld
3003	ER4043 or ER5356	Either works for general fabrication
5052	ER5356	4043 is acceptable for low magnesium alloys like 5052
5083, 5086, 5456	ER5356 or ER5183	Do not use 4043 on high magnesium alloys
6061, 6063	ER4043 or ER5356	4043 is more crack resistant; 5356 gives more shear strength and better anodized color
6061 to 5052	ER5356	Common dissimilar joint
A356 and other castings	ER4043	Silicon fillers suit cast alloys
Most 2xxx and 7xxx	Not arc weldable in most cases	A few exceptions, such as 2219 and 7005, use special fillers

Key points

Sustained high temperature: avoid fillers with more than 3% magnesium, such as 5356, when service is above about 150°F (65°C). They can become sensitive to stress corrosion cracking. Use 4043 or 5554 as the maker advises.
Anodizing: 4043 turns dark gray after anodizing. Use 5356 for a better color match.
Feeding: 5356 is stiffer and feeds more easily through a MIG gun. 4043 is soft and often needs a spool gun or push-pull.
Heat treat: 4043 welds do not respond to heat treatment the way the base metal does. Strength in the weld area drops on 6061-T6.
Use 100% argon or argon-helium gas. No CO2.
Clean oxide with a dedicated stainless brush just before welding.

Common mistakes

Using 4043 on 5083 boat plate.
Using 5356 on parts that run hot.
Feeding 4043 through a long steel liner.
Anodizing a 4043 weld and expecting a color match.

Governing standards: AWS A5.10; AWS D1.2 (structural aluminum).

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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